High-frequency apparatus and method



March 15, 1949. w, W, HANSEN ET AL 2,464,229

HIGH-FREQUENCY APPARATUS AND METHOD Original Filed July 2, 1940 IIIIIIIIIIIII Patented Mar. 15, 1949 UNITED STATES PATENT OFFICE HIGH-FREQUENCY APPARATUS AND METHOD Application September 2, 1942, Serial No. 457,096, which is a division of application Serial No.

Divided and this application November 10, 1943, Serial No. 509,668

343,528, July 2, 1940.

This application is a true division of our copending application, Serial No. 457,096, iiled September 2, 1942, and now Patent No. 2,410,063, issued October 29, 1946, which is itself a true division of our application, Serial No. filed July 2, 1940, now Patent No. 2,311,658, issued February 23, 1943.

This invention relates, generally, to high frequency tube structures having enclosed oscillatory circuits of the type disclosed in Patent No. 2,242,275, issued May 20, 1941, in the name of Russell H. Varian, one of the inventors herein, and the invention has refeernce more particularly to novel improvements in this type of structure operating at frequencies of the order of 109 cycles per second.

The principal object of the present invention is to provide a novel practicable embodiment of high frequency tube structure utilizing principles disclosed in the above-identified application, the device of the present invention employing a pair of hollow resonators land being operable as a self-oscillator, an amplier or a detector at will.

Another object of the present invention is to provide improved high frequency tube structures of the velocity modulation type using non-planar grid structures for improving the operation thereof.

Still another object of the present invention is to provide an improved electron beam cavity resonator or other high frequency eld apparatus in which the lower velocity electrons of the beam are prevented from proceeding through the resonator or field.

A still further object of the present invention is to provide improved electron beam 'velocity modulation electron discharge apparatus in which the effects of non-uniformity of the electron bunches are minimized or neutralized.

Other objects and advantages will become apparent from the specication taken in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings,

Fig. 1 is a longitudinal view partly in section of one embodiment of the invention.

Fig. 2 is a cross-section with parts broken away along the line 2-2 of Fig. 1.

19 Claims. (Cl. 315-6) porting the electron emitter structure 20.

Fig. 3 is a cross-section along the line 3 3 of Fig. 1.

Similar characters of reference are used in the above figures to indicate corresponding parts.

Referring now to the drawing, the novel tube structure is shown in Fig. 1, comprising a central tubular shell I, and having spaced hollow resonators 2, 3 that are secured at their peripheries to the inner wall of shell I. Resonator 2 is formed by a rigid wall 2' abutting an internal shoulder of shell I, and a flexible wall 2 connected to the end of shell i. Resonator 3 has similar walls 3 and 3". Resonators 2, 3 thus form enclosed electron-excitable resonant circuits of the type disclosed in Patent No. 2,242,275. These cavity resonators are shown of toroidal or substantially doughnut shape, the inner walls terminating in opposed grids 4, 5, and 6, 1. Grid 4 is mounted in a tube 9 which connects wall 2 to an end plate I0, which in turn supports a tubular member II to which an end bell I2 of glass is fastened by a n'ietal-to-glassl seal I3. Similarly, grid 1 is mounted in a tube I4 which connects wall 3" to an end plate I5, which, supports a tubular member I6 to which an end bell I'I of glass is fastened by a metal-to-glass seal I8. Grid 5 is supported in a tube 9' mounted in wall 2', and grid 6 is similarly mounted in tube I4 connected to wall 3.

The end bells I2 and I'I, the cavity resonators 2 and 3, shell I, and connected aligned tubes 9 and i4 are evacuated, the bell I2 being sealed 01T, as at I9. End bell I2 contains an electron emitter structure 29, having an electron emitting surface 2! heated by a iilament 22, having supply leads 23 and 24 passing through a press 25 sivige electron emitter structure is so arranged that the electrons emitted from surface 2l are collimated into a stream that will passA through the grids 4, 5, and l. Grid 34 is an accelerating grid, and grid 35 is used to obtain a more uniform electrostatic eld.

The structure of Fig. 1 is shown connected for serving as an amplifier or detector, although by changing the connections, the same may be made `to serve as an oscillator, if desired. In this figure, ultra high frequency energy of the resonant frequency of resonator 2 is supplied thereto by way of input lead 39 shown in the form of a concentric transmission line having a coupling loop El extending within resonator 2 for coupling to the field thereof. Resonator 2 thus acts as a buncher resonator. Cavity resonator 3 acts: as a catcher for amplified electromagneticv energy, as is disclosed in the above mentioned Patent No. 2,242,275. s"

Atmospheric pressure, acting upon the flexible outer end walls 2" and 3 of cavity resonators 2 and 3 supporting grids Ll and l, tends to cause these walls to deect longitudinally inwardly so that grid Il tends to approach grid 5, and grid 'I tends to approach grid The amount of deflection of these grids under the effect of atmospheric pressure is controllable at will by the use of the novel tuning means of this invention. This tuning means comprises end plates Ill and I5 that are rigidly connected to tubes 9 and I4 respectively.

End plates ill and l5 are urged towardre'ach other by springs lil, the thrust of the, springs' 14, in addition to that produced by atmospheric pressure, being resisted by struts 92, 92' and 93, 93". Three pairs of substantially aligned struts angularly spaced 120 apart are used. Of these, two pairs of struts 93, 93' rest directly upon stationary ring d6, whereas the remaining pair of struts 92 and 92 bear upon the outer sides of the arcuate levers 94 and SLlIthat are pivoted at on stationary thrust ring d5, as seen in Fig. 2.

The thrust of strut $2 is transmitted to lever 94 and then through ball 53 constrained to move in a race T6 concentric with pivot l5 to stationary thrust ring 015. The thrust of strut 92 is similarly transmitted through -lever 94 to ringr 46. Levers 9d and all are fastened together by a yoke 95. A lug e6 is fastened to thrust ring 46 and threaded for an adjusting screw 91. A. coil spring 58 urges members 95 and @t toward each other and these members are heldv apart by a strut 99. By adjusting screw 97, levers 96 andA 94' are caused to rotate about pivot l5, thereby changing the angularity of struts 32 and 92 and causing the end plates lll and t5 to tip slightlyv relative to stationary thrust ring fit. This tip;- ping of the. end plates changes the average 'spacing of grids t and liV of the buncher and grids 1 and 8 of the catcherf effecting an alteration in the gang tuning of these hollow resonators.

The tube of Fig. 1 is shown operating as a receiver, the same being provided with grids 1l and 12 for effecting detection. End bell l1 contains the getter coils 2l and 28 and a cylinder li! carrying grids 'il and l2. Cylinder 'lil surrounds and shields plate element 33 and is maintained through supply lead 'i3 at such a voltage that a part of the electrons passing grid 35 will be reflected by grids li and 'i2 and hence are provided` from reaching plate elemate 3?. Grid il is pref'- erably placed at an angle to the axis of the tube to prevent the. reflected electrons. from. again:

passing through grid l. The number off electrons reaching plate element .33 can thus be made to vary with the strength of` electromagnetic oscilllations in cavity resonator 3, resulting in detec- 'tion of such oscillations.

ceiving antenna or other source for supplying.

the signal to resonator 2. Additional concentric line terminal posts are shown attached to the buncher and catcher resonators for the purpose of altering the functionsv of the tube, when desired. Thus, if a terminal post 39 of the catcher is coupled back as by a concentric line to a terminal post 39 of the bunchen the apparatus will serve as an oscillator. Otherwise it also serves as an amplifier.

This tube structure is also shown provided with a space charge control grid 68, as when modulation is desired, this grid being shown provided with a terminal lead 69. This grid is shown carried by focussing ring lll, which in use would normally hav a collimating effect upon the electron stream.

Grids d, 5, and 'I are shown shaped like Very shallow cones with their apexes facing each other. The electrostatic eld between opposed grids -5 and 6--1 is of such a nature that low velocity electrons are caused to move radially outward. and beyond the strong electrostatic field existing between these opposed grids, where the presence of such electrons may be undesirable.

The grid pair il-5 also has a'further advantage. As is described in above-mentioned Patent No. 2,242,275, the alternatingY nield between grids 4- and 5 serves to periodically vary the velocity of, or velocity modulate, the electrons of the beam. These electrons, while passing through the neidfreedrift space within tubes 9 and l2 and shell i, are bunched or grouped by the actionof the faster electrons overtaking the vslower ones. It has been discovered that this bunching is re,- tarded in the center of the beam due to the mutual repulsion of the electrons, so that it takes a longer drift distance for these center electrons to bunch up than for electrons at the edge of the beam. This causes the bunch to be non-uniform; that is, by the time the electrons arrive at the catcher resonator, the beam has greater electron density at. the edges than at the center. This decreases the power extracted byv the catcher resonator, and thus decreases the amplification or output of the device. However, by reducing the' spacing between grids 4. and 5 at the center of the beam, with respectv to the spacing at the edge of the beam, as shown by grids d and 5 of Fig. 1, this non-uniformity of the electron bunch is reduced, by increasing the impressed Velocity modulation for the center electrons, resulting in improved operation.

The effects of this bunch non-uniformity are also minimized by makingy the drift distance longer for electrons centrally of the beam than forelectrons at the edge of the beam, as shown in Fig. l, by the opposite taper of the slats of grids 5y and 6.

The inner walls 2' and 3 of both cavity resonators 2, 3; supporting'g-rids 5 and t are` of large @liess-'section` and, thereby serve to readily transmit.. theheat generated' in grids 5, ii to central .shell I,- wherefrom it may be dissipated iny a known manner.; Thecross-section of the electron pathy between grids E and 6 is enlarged transversely of` the stream which structure minimizes diffusion of the electron stream due to electrostatic forces.

As many changes' could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all. matter containedv in the above amazes description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. High frequency apparatus comprising means for forming a concentrated electrostatic field, means aligned with said field for projecting an electron beam through said field, and means along the path of said beam for moving low velocity electrons of said beam radially outward of said beam and beyond said field.

2. High frequency apparatus comprising means including a cavity resonator and a source of high frequency energy coupled thereto for forming a concentrated electrostatic field, means aligned with said resonator for projecting an electron ybeam through said resonator in amanner to interact with said field, and means along the path of said beam for moving low velocity electrons of said beam radially outward of said beaml and beyond said field.

3. High frequency apparatus comprising a cavity resonator including a pair of multiply-apertured conical grids having aligned axes, means coupled to said resonator for exciting said resonator to form a concentrated high frequency electrostatic field between said grids, and means aligned with said grids for projecting an electron beam axially through the apertures of said grids for interaction with said field whereby low velocity electrons of said beam are moved radially beyond said field, and high velocity electrons proceed through said grids and interact with said field.

4. High frequency apparatus as in claim 3 wherein said conical grids have their apices in opposed aligned relation.

5. High frequency electron discharge tube apparatus comprising a grid structure having a plurality of conically arranged linear elements, and means aligned with said grid structure for projecting an electron stream through said grid along the axis of said conical arrangement.

6. High frequency apparatus comprising means forming a hollow cavity resonator having an apertured wall, and a grid structure mounted within said aperture, said grid structure comprising a plurality of conically arranged linear elements.

7. High frequency discharge tube apparatus comprising a grid having a plurality of alternately long and short conically arranged linear elements, and means aligned with said grid for projecting a stream of electrons through said grid along the axis of said conical arrangement.

8. High frequency apparatus comprising means forming a cavity resonator having an apertured wall, said aperture containing a plurality of alternately long and short conically arranged linear elements.

9. High frequency apparatus as in claim 8 further comprising means aligned with said wall for projecting a stream of electrons through said apertured wall and into said resonator along the axis of said conical arrangement.

10. High frequency apparatus comprising a hollow cavity resonator having opposed apertured walls, and a grid in each of said walls, each of said grids comprising a plurality of yconically arranged linear elements, said two conical arrangements having their apices facing one another.

11. The method of operating high frequency electron discharge tube apparatus comprising the steps of producing a concentrated oscillating high frequency electromagnetic field having a radial field strength gradient and projecting a beam of electrons through said field.

12. A method of operating high frequency electron discharge tube apparatus comprising the steps of producing a concentrated oscillating electromagnetic field having a radial field strength gradient, projecting an electron beam through said field to be velocity modulated thereby, moving low velocity electrons of said beam radially thereof and beyond said field, and utilizing the remainder of said electrons for producing corresponding high frequency oscillations.

13. Velo-city modulation electron discharge apparatus comp-rising a pair of spaced cavity resonators, each having a pair of electron-permeable electrodes dening a gap therebetween, means dening a field-free drift space between said resonators, and means aligned with said resonator for projecting an electron beam successively through one of said resonator gaps, said drift space, and the other of said gaps, the electrodes defining said first gap having diiering spacings over the cross-section of said beam, whereby the effects of non-uniformity of the electron vbunch are decreased.

14. Velocity modulation electron discharge apparatus comprising means for producing an electron beam, means along the path of said beam' for velocity modulating the electrons of said beam, means along said beam path for causing said modulated electrons to form into bunches and means along said beam path for extracting high frequency energy from said bunched beam, said velocity modulating means including means for decreasing the non-uniformity of the electron bunches arriving at said extracting means.

15. Apparatus as in claim 14, wherein said velocity modulating means comprises a cavity resonator having a pair of electron-permeable electrodes defining a gap through which said beam passes, said electrodes being non-planar.

16. Apparatus as in claim 14, wherein said modulating means comprises a cavity resonator having a pair of electron-permeable electrodes dening a gap through which said beam passes, said electrodes having varying spacings across the cross-section of said beam.

17. Apparatus as in claim 16, wherein said electrodes have closer spacing at the center of said beam than at the edges of said beam.

18. High frequency apparatus comprising means for producing a stream of electrons, means along the path of said stream for velocity moduating said stream, means along said stream path defining a field-free drift space wherein said modulated beam becomes bun-ched, and means along said stream path for extracting high frequency energy from said bunched stream, said drift-space-defining means providing diiferent lengths of electron path therein for electrons at different portions of said beam, to minimize the effects of non-uniformity of said electron bunches.

19. Apparatus as in claim 18, wherein said drift space means provides a longer drift distance for electrons at center of said beam than at the edges thereof.

WILLIAM W. HANSEN'. RUSSELL H. VARIAN. SIGURD F. VARIAN.

(References on following page) '7 REFERENCES -mTED The following references are of record in the Number 'le of this patent:

UNITED STATES `PA'IEIL\T'1XE` Name Date Southworth Apr. 11, 1939 Zottu et a1 Jan. 14, 1941 White Mar. 18, 1941 Heil Mar. 18, 1941 Varian et a1 July 29, 1941 Von Ardenne Oct. 7, 1941 Number 

